﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    public interface  Itool
    {
       int add(int i, int x);
    }

    public class tool : Itool
    {
        public virtual int add(int i, int x)
        {
            return i + x;
        }
    }
}
